For former world number ones Venus Williams and Jelena Jankovic, their second- round clash at Charleston was a defining moment in the careers of two women desperate to claw their way back to the top.

Once regarded as the best in the world, both have seen their careers stall -- Williams slipping to number 87 and seventh-seeded Jankovic losing in the opening round at her last three tournaments.

But their fortunes took very different turns at Wednesday's Family Cup tournament, with America's Williams defeating Serbia's Jankovic in straight sets, 7-5 6-0.

The victory is a huge boost to Williams' comeback campaign after a long absence due to illness.

Venus, who last won the U.S. tournament in 2004, is continuing her recovery from Sjogren syndrome, an auto-immune disorder.

"Honestly, I don't know how it went that nicely for me. Everything just landed, and she hit a few errors, and that helped me a lot," she said on the WTA website.

Jankovic meanwhile, will be seeking to halt her career spiral after bowing out of the clay season opener.

She had gone into the match the favorite, after beating Williams in their last four meetings on clay, and admitted her lack of a coach was a factor in her defeat.

"I'm in negotiations to find a coach, to get a coach, and I really want to because it's difficult like this, not having anyone, especially when I have to work on some technical things and get the shots right on track," she said.

"It's little things here and there that make a big difference, and it's important to have someone to help you.

"I'm at the stage of my career where I'm getting older and maybe need more help than before, where I could do it alone at times, or with a hitting partner.

"The next few years I'm going to play, I want to try to give my best, and I want to improve. I still want to work hard and try to get better as a player."

Venus will now face Australian Anastasia Rodionova, ranked 96.

Also through to the third round is New Zealand's Marina Erakovic, ranked 17. She beat Georgia's Anna Tatishvili 7-5 6-3, to advance to a meeting with fifth-seeded American Serena Williams Thursday.